Rosin size



Patented Dec. 30, 1941 BOSIN SIZE Arthur C. Dreahiield, Wilmington,Del., assignor to Hercules Powder Company, Wilmington, DeL, acorporation of Delaware H No Drawing. Application June 30, 1939,

Serial No.282,203

, scheme. (on. lo 17s) This "invention relates to an aqueous rosin sizedispersion. More particularly, it relates to an aqueous rosin sizedispersion characterized by stability after being frozen.

Rosin size containing asubstantial proportion of free rosin dispersedtherein presents many advantages over substantially neutral rosin sizein the sizing of paper,textiles, and fibrous materials.

. Such rosin size dispersions are being used commercially to aconsiderable extent at the present time. The usual method of preparationof these dispersions consists in melting the rosin to be dispersed,causing to react, therewith a small fraction of the alkali necessary to.bring about completesaponiflcation of the rosin, then dispersing themixture of rosin and rosin soap in water. Such dispersions have thegreat disadvantage of being completely broken ii the rosin size becomesfrozen. Remelting produces an agglomeration oi rosin, thereby renderingthe size, completely unfit for use. Shipping of such rosin sizedispersions at below freezing temperatures is, therefore, not possible.size dispersion must be prepared in situ at the point of use or must beshipped only in nontreezing weather. Both of these alternatives detractmaterially from the commercial exploitation of rosin size containing asubstantial amount of free rosin.

It is an object of this invention to avoid the above ireezingdiiliculties of aqueous rosin size dispersions containing a substantialproportion of free rosin and to provide sucha dispersion which may beshipped in freezing weather without danger of destroying the dispersion.

In accordance with this invention, Ihave found that an aqueous rosinsize dispersion containing a major proportion of free rosin Land a minorproportion of rosin soap,prepared with the aid of aprotective colloid;may be stabilized against damage by freezing by addition of a smallamount of an anti-freeze stabilizing agent, i. e. an agent which notonly lowers the freezing point of the size dispersion but alsostabilizes it against coagulation upon freezing. Anti-freeze stabilizingagents which I have found to be suitable for this purpose are, forexample, dried whey, sugar, corn syrup, glycerol, ethylene glycol; etc.As protective colloids useful in the preparation of the dispersions,such materials asacid or alkaline solutions of casein, egg albumin orsoybean protein may be employed. The rosindisperslon may also contain awax, such as a parailin wax, as a modiiying agent for the rosin. 1 I

When rosin is saponified with suiilcient alkali to leave less than about40 per cent of free rosin, the rosin soap formed actsas a dispersingagent for the free rosin and a'clear dispersion results.

As a result, the

above 40 per cent, however, the product is not completely soluble inwater and forms an emulsion.

In practicing my present invention I saponify rosin by heating thelatter to a molten condition, adding an amount of alkalisolution, suchas sodium hydroxide, potassium hydroxide or sodium carbonate, which issufficient to saponify less than about 65% of the rosin, preferablyabout 8 to about 35 per cent of the rosin, carrying out thesaponiiication with efllcient mechanical agitation. Then, to thepartially saponifled rosin I add a protective colloid such as, forexample, a casein solution carryingout the dispersion with rapid andefllcient agitation so as to produce a dispersion of as small particlesize as possible. After dispersion is complete, I add water to dilute toa desirable solids concentration for efficient handling and use,preferably about 50 per cent solids concentration. I add the anti-freezestabilizing agent to the dispersion alongwith the water.

, the desired anti-freezing eflect.

When the amount of tree rosin is substantially The amount of protectivecolloid necessary to produce suitable dispersions will vary with theparticular material used and the amount of jsaponified rosin present.With a slightly acid solution of casein, .for example, the protectivecolloid ,may be present in amounts within the range of about one toabout 25 per cent by weight based on the weight of rosin. 1

I In testing my anti-freezing aqueous rosin size ,dispersionsagalnstexposure to freezing condiconditions to which rosin size might beexposed during shipment and storage prior to use.

1 I prefer to use an amount of the anti-freeze stabilizing agent-whichis suflicient to enable the rosin size dispersion to withstand at least9 freezing cycles as described above. Thisamount will vary withdifferent agents. ,Thus, for example, I find that additionof about 4 percent of dried whey based on the weightof size, or about 8 per cent ofsugar, or, about .12 per cent of corn syrup or glycerine is sufllcientto produce I find it impossible to establish a definite operable rangesince the various agentsvary somewhat in their effect. A limitingfactorin determining the maximum amount of the agentlto be added is thecost. 1

As illustrative of my invention I may cite the following typicalexamples:

Example I The anti-freezing stabilized dispersions prepared inaccordance with this invention may be used for sizing fibrous materials,such as paper,

a board, textiles, etc.

It will be understood that the details and examples hereinbefore setforth are illustrative only, and that the invention as broadly describedand claimed is in no way limited thereby.

weight slightly acid aqueous solution of casein I are added in about /2minute and more rapid agitation continued for about 4 minutes to effectthe dispersion. Cold water sufficient to' give a concentration of about50 per cent solids is then added together with 12.5 parts by weight ofdried whey.

The rosin size dispersion produced in accordance with the above examplewill withstand at least 10 of the freezing cycles described abovewithout impairing its value as a sizing composit'on. Paper sized withthe above size after 10 freezing cycles became sized to the same extentas paper sized with the unfrozen size.

To accomplish the same result I may substitute for the dried whey of theabove example, 26 parts by weight of sugar, 40 parts by weight of cornsyrup or 40 parts by weight of glycerol. Although these are the amountswhich I have found necessary to'give a size to withstand at least 9 ofthe freezing cycles, I may use a smaller amount in the event thatstability to less severe cold atmospheres is desired.

Example I! To 150 parts by weight of G, gum rosin heated to about 105 C.and agitated with an efllcient stirring device is added over a period ofabout one minute a solution of 1.8 parts by weight of sodium hydroxidein'8.5 parts by weight of water. The agitation is continued for aboutmin utes and the temperature raised to about 99 C.

' Then 24 parts by weight oi. a 12.5 per cent by weight slightlyacid'aqueous solution of casein are added and vigorous agitationcontinued for about 4 minutes to eifect the dispersion. 'Then' 12.5parts by weight of dried whey dissolved in an'amount of water sufficientto give 50 per cent by weight solids concentration are added. The rosinsize dispersion produced in accordance with the above procedure willwithstand at least 10 of the freezing cycles described above and will besatisfactory for shipment without damage under freezing conditions.

The rosin size dispersions containing dried whey are sometimes subjectto'putrefaction. A preservative may be included to prevent suchputrefaction of the dried whey.

In the example of rosin size illustrated in Example I above, the alkaliemployed is sufflcient to saponify approximately 25 per cent of therosin, thus'leaving about 75 per cent of the rosin as the free acid inthe size. In Example 11 the amount of free rosin is about 90 per cent. Imay vary the amount of caustic added from the amount necessary tosaponify about 8 per cent up to the amount necessary to saponify about35 temperatures in the range of 15 to rosin size consisting offrom about65 to about 7 92 per cent by weight of free rosin and from about 8 toabout 35 per cent by weight of rosin soap, a-protective colloid, and anagent selected from the group consisting of dried whey, sugar, cornvsyrup, glycerol, and ethylene glycol, said agent being employed in anamount sufficient to render the dispersion stable to coagulation uponrepeated freezing at temperatures in the range of -15 to -23 F. for 16hours. a

2. An-aqueous sizing dispersion comprising a rosin size consisting offrom about 65 to about 92 per cent by weight of free rosin and fromabout 8 to about 35 per cent by weight of rosin soap, a protectivecolloid, and an amount of dried whey sufllcient to render the dispersionstable to coagulation upon repeated freezing at temperatures in therange of 15 to 23? F. for 16 hours. 7 a

3. An aqueous sizing dispersion comprising a rosin size consisting offrom about 65 to about 92 per cent by weight of iree rosinand from about8 to about 35 per cent by weight of rosin soap, a protective colloid-andan amount of sugar sufficient to render the dispersion stable tocoagulation upon repeated freezing at temperatures in the range of 15 to-23 F. for 16 hours.

4. An aqueous sizing dispersion comprising a rosin size consisting offrom about 65 to about 92 per cent .by weight of free rosinand fromabout 8 to about35 per cent by-weight of rosin soap, a protectivecolloid, and an amount of corn syrup sufiicient to render the dispersionstable to coagulation upon repeated freezing'at temperatures inthe rangeof 15 to -23 F. for

16 hours. v

5. An aqueoussizingdispersion comprising a rosin size consisting of fromabout 65 to about 92 per cent by weight of free rosin'and from about 8to about 35 per cent by weight of rosin soap, between about 1 and about'25 percent of a protective colloid based on'the weight of rosin, about4 per cent of dried whey based on the total weight of the dispersion,said dispersion being stable to coagulation upon repeated freezing at-23 F.

for 16 hours.

6. An aqueous sizing dispersion containing approximately 50 per cent byweight of solids and comprising a rosin size consisting of from about 65to about 92 per cent by weight of free rosin and from about 8 to about35 per cent by weight of rosin soap, between about 1 and about 25 percent of caseinbased on'the weight of the rosin, and about 4 percent ofdriedwhey'based on the total weight of the dispersion, said dispersionbeing stable to coagulation upon repeated freezing at temperatures inthe range of -l5 to 23 F. for 16 hours.

ARTHUR C. DRESHFIELD.

